The detergent formulator is constantly facing cleaning and stability issues. Unit dose products can be more challenging than loose powders or liquids. Detergents in unit dose form have associated constrains in terms of volume that imply limitations in terms of the amount of actives.
Most if not all the cleaning ingredients can be susceptible to degradation to a greater or lesser extent. In unit dose products the different ingredients are in close proximity to one another this can negatively affect the stability of the product. The current trend is to reduce the size of the unit dose product making the cleaning and stability issues more of a challenge.
In recent years cleaning and stability of cleaning products have been impacted by the tendency to eliminate phosphate from cleaning formulations. Phosphate is not only an excellent cleaning active but also contributes to product stability by adsorbing moisture from the surrounding environment and/or from the product itself.
Another added complication that the detergent formulator faces is that different actives can be in different physical forms, some of them are in liquid form and some other in solid form. In order to have a cleaning composition in one physical form processing of ingredients in a different form is required. For example, organic dispersants such as organic polymers and organic builders are usually synthesized in liquid form. A great deal of work and high cost is associated with the transformation of these materials into particles in order to introduce them into products in solid form.
For example, a great deal of work has been done to convert organic polymers into particles. US 2012/0225450 A1 relates to carboxyl-containing polymer in solid form. These polymers are usually synthesized in aqueous solution. WO2011/133483 relates to a particle comprising an organic builder, in particular an aminocarboxylate builder. Aminocarboxylate builders are usually synthesized in aqueous solution.
The usual form in which aminocarboxylate and other dispersants, for example salts of glutamic acid N,N-diacetic acid (GLDA), methyl glycine diacyl acid (MGDA) are available is as liquid solutions with different active content. After drying the solution, the powder or granules, especially when obtained in the amorphous state, usually show hygroscopic and deliquescent properties which make them difficult to use in detergents. Moreover, the granules obtained from a granulation process (such as fluid bed granulation) are somewhat brittle and thus cannot grow easily to the required size, resulting in slow processing and lots of fines. In addition, whether in powder or granule form, the material can exhibit hygroscopic and deliquescent properties, and this will render the material sticky and thus introduce storage, handling, and manufacturing problems. These problems can be more acute in the case of dispersants such as aminocarboxylic acids and organic polymers. WO2011/076769 A1 addresses the problem by providing a process to make coated GLDA particles.
Flow properties of particles are critical in many ways. During manufacture of the particles themselves, they must flow smoothly relative to one another, e.g. in a fluid bed. Additionally, they must then be successfully transported to storage and transport containers. Finally, they must again be transported from storage and fed into a powder or tablet manufacturing facility. Flow problems arise due to several causes. For dispersants, poor flow can be due to theirs hygroscopic properties.
Another problem associated with unit-dose products, in particular with water-soluble packs comprising a cleaning composition and an enveloping material is the interaction between the cleaning composition and the enveloping material. The enveloping material is water-soluble and usually contains a certain amount of water thus the presence of water in the cleaning composition could affect the integrity and properties of the film.
A further problem associated with multi-compartment unit dose products, is that the enveloping material is usually moisture permeable, allowing the transfer of moisture across compartments, negatively impacting on the stability of the product.
The objective of this invention is to provide a product that has a good environmental and cleaning profile, it is stable upon storage and it is favourable from a process viewpoint.